1. Field of the Invention
This invention relates to portable battery-operated lighting devices, and in particular to improvement in hand held flashlights of the type which have means for enclosing a beam projecting reflector, means for holding and electrically coupling a bulb, means for retaining and electrically coupling batteries, and means for changing the focus of light therefrom between a narrow beam and a broad beam.
2. Description of the Prior Art
Generally, hand held flashlights provide a casing enclosing a plurality of batteries, a light bulb, switch means to electrically connect the batteries to the bulb, and a reflector to concentrate and project the light emanating from the bulb in the form of a beam. Many configurations embodying substantially similar elements of these types have been disclosed. Each differs in either the general form factor of the flashlight or the nature of the elements within the flashlight, but each has also resulted from effort to improve performance and reliability. Among the more recent developments is that represented by U.S. Pat. No. 4,286,311 wherein a rugged, heavy-duty flashlight is described. This flashlight is hermetically sealed to prevent intrusion of moisture and dirt and is readily adjustable to provide illumination ranging from narrow concentrated light beam to a broad diffuse, but limited, beam. Additionally, it provides a manually operated electric switch having a rotary contact engaging a stationary contact such that when the switch is actuated the rotary contact moves axially against the stationary contact thus wiping the contacts against each other to clean the contact surfaces.
Heretofore, flashlights of the above types have, by their construction, a propensity to cause damage to the batteries, diminishing their life. This has resulted from the contact pressure holding the batteries in position and making electrical contact being placed entirely on the center terminal of a standard dry cell battery, which pressure can cause front end cave-in of the cell. Additionally, such devices of prior art have provided loose or inadequate electrical contact which tends to diminish illumination. In those devices which provide means for varying the light from a narrow-beam to a broad-beam condition, a substantially large opening is required in the reflector to enable the bulb and its holder to be translated in relation to the reflector in order to change the focus. The holder is generally of a substantially larger diameter than the bulb. Moreover, the methods for accomplishing the relative translation between the bulb and the reflector often introduce tilt or offset to the bulb. Both such factors result in degradation of the illumination from the flashlight. Finally, the advent of rechargable batteries and the continuing requirement for operational silence in applications such as use by peace officers or security forces, have given impetus to continued development.